let a = new Set([1,2,3])
let b = new Set([2,3,4])

console.log(a)

let c = [1,2,3]
let d = [2,3,4]
c = [...c,...d,5]
console.log(c.concat(d))
c = new Set(c)
console.log(c)
c=[...c]
console.log(c)
let map = new Map();
map.set('a','123')
console.log('map',map.get('a'))